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Abstract:

A light-emitting diode (LED) structure and a method fro manufacturing the
same. The LED structure includes a substrate, an illuminant epitaxial
structure, first conductivity type and second conductivity type contact
layers, a transparent insulating layer, first and second reflective
layers, first and second barrier layers, and first conductivity type and
second conductivity type electrodes.

Claims:

1. A light-emitting diode (LED) structure, comprising: a substrate; an
illuminant epitaxial structure, comprising: a first conductivity type
semiconductor layer, disposed on the substrate; an active layer, disposed
on a first part of the first conductivity type semiconductor layer and
exposing a second part of the first conductivity type semiconductor
layer; and a second conductivity type semiconductor layer, disposed on
the active layer and having a conductivity type different from that of
the first conductivity type semiconductor layer; a first conductivity
type contact layer, disposed on the second part of the first conductivity
type semiconductor layer; a second conductivity type contact layer,
disposed on the second conductivity type semiconductor layer; a
transparent insulating layer, covering the illuminant epitaxial
structure, the first conductivity type contact layer and the second
conductivity type contact layer and having a surface, wherein the
transparent insulating layer comprises a first contact hole and a second
contact hole respectively exposing a part of the first conductivity type
contact layer and a part of the second conductivity type contact layer; a
first reflective layer, extending on and covering the first contact hole
and a part of the surface of the transparent insulating layer; a second
reflective layer, extending on and covering the second contact hole and
the other part of the surface of the transparent insulating layer; a
first conductivity type electrode, disposed on the first reflective layer
and filling up the first contact hole; and a second conductivity type
electrode, disposed on the second reflective layer and filling up the
second contact hole.

2. The LED structure according to claim 1, further comprising a first
barrier layer disposed between the first reflective layer and the first
conductivity type electrode and a second barrier layer disposed between
the second reflective layer and the second conductivity type electrode.

3. The LED structure according to claim 1, wherein the first conductivity
type electrode and the second conductivity type electrode are disposed in
the same plane.

4. The LED structure according to claim 1, wherein the number of the
first conductivity type contact layer and the number of the second
conductivity type contact layer are both at least one.

5. The LED structure according to claim 1, wherein a material of the
transparent insulating layer comprises spin on glass (SOG), a high
polymer, SiO2 or TiO.sub.2.

6. The LED structure according to claim 1, wherein a thickness of the
transparent insulating layer is between 0.5 μm and 100 μm.

7. The LED structure according to claim 1, wherein a sidewall of the
first contact hole and a sidewall of the second contact hole are both
inclined relative to the illuminant epitaxial structure.

8. The LED structure according to claim 1, wherein the transparent
insulating layer comprises at least one pattern structure.

9. A light-emitting diode (LED) structure, comprising: a substrate; an
illuminant epitaxial structure, comprising: a first conductivity type
semiconductor layer, disposed on the substrate; an active layer, disposed
on a first part of the first conductivity type semiconductor layer and
exposing a second part of the first conductivity type semiconductor
layer; and a second conductivity type semiconductor layer, disposed on
the active layer and having a conductivity type different from that of
the first conductivity type semiconductor layer; a first conductivity
type contact layer, disposed on the second part of the first conductivity
type semiconductor layer; a second conductivity type contact layer,
disposed on the second conductivity type semiconductor layer; a first
reflective layer, stacked on the first conductivity type contact layer; a
second reflective layer, stacked on the second conductivity type contact
layer; a transparent insulating layer, covering the illuminant epitaxial
structure, the first reflective layer and the second reflective layer and
having a surface, wherein the transparent insulating layer comprises a
first contact hole and a second contact hole respectively exposing a part
of the first reflective layer and a part of the second reflective layer;
a first conductivity type electrode, disposed on the transparent
insulating layer and filling up the first contact hole; and a second
conductivity type electrode, disposed on the transparent insulating layer
and filling up the second contact hole.

10. The LED structure according to claim 9, further comprising: a first
barrier layer, disposed between the first contact hole, a part of the
surface of the transparent insulating layer and the first conductivity
type electrode; and a second barrier layer, disposed between the second
contact hole, the other part of the surface of the transparent insulating
layer and the second conductivity type electrode.

11. The LED structure according to claim 9, wherein the first
conductivity type electrode and the second conductivity type electrode
are disposed in the same plane.

12. The LED structure according to claim 9, wherein the number of the
first conductivity type contact layer and the number of the second
conductivity type contact layer are both at least one.

13. The LED structure according to claim 9, wherein a material of the
transparent insulating layer comprises spin on glass (SOG), a high
polymer, SiO2 or TiO.sub.2.

14. The LED structure according to claim 9, wherein a thickness of the
transparent insulating layer is between 0.5 μm and 100 μm.

15. The LED structure according to claim 9, wherein a sidewall of the
first contact hole and a sidewall of the second contact hole are both
inclined relative to the illuminant epitaxial structure.

16. The LED structure according to claim 9, wherein the transparent
insulating layer comprises at least one pattern structure.

17. A method for manufacturing a light-emitting diode (LED) structure,
comprising: forming an illuminant epitaxial structure on a substrate,
wherein the illuminant epitaxial structure comprises: a first
conductivity type semiconductor layer, disposed on the substrate; an
active layer, disposed on a first part of the first conductivity type
semiconductor layer and exposing a second part of the first conductivity
type semiconductor layer; and a second conductivity type semiconductor
layer, disposed on the active layer and having a conductivity type
different from that of the first conductivity type semiconductor layer;
forming a first conductivity type contact layer on the second part of the
first conductivity type semiconductor layer; forming a second
conductivity type contact layer on the second conductivity type
semiconductor layer; forming a transparent insulating layer covering the
illuminant epitaxial structure, the first conductivity type contact layer
and the second conductivity type contact layer; forming a first contact
hole and a second contact hole in the transparent insulating layer,
wherein the first contact hole and the second contact hole respectively
expose a part of the first conductivity type contact layer and a part of
the second conductivity type contact layer; forming a first reflective
layer extending on and covering the first contact hole and a part of a
surface of the transparent insulating layer; forming a second reflective
layer extending on and covering the second contact hole and the other
part of the surface of the transparent insulating layer; forming a first
barrier layer and a second barrier layer respectively covering the first
reflective layer and the second reflective layer; forming a first
conductivity type electrode on the first barrier layer and filling up the
first contact hole; and forming a second conductivity type electrode on
the second barrier layer and filling up the second contact hole.

18. The method for manufacturing an LED structure according to claim 17,
wherein the first conductivity type electrode and the second conductivity
type electrode are disposed in the same plane.

19. The method for manufacturing an LED structure according to claim 17,
wherein the step of forming the transparent insulating layer comprises
forming a transparent oxide layer by spin coating to serve as the
transparent insulating layer.

20. The method for manufacturing an LED structure according to claim 17,
wherein the step of forming the first contact hole and the second contact
hole further comprises making a sidewall of the first contact hole and a
sidewall of the second contact hole be both inclined relative to the
illuminant epitaxial structure.

21. The method for manufacturing an LED structure according to claim 17,
further comprising forming at least one pattern structure in the surface
of the transparent insulating layer between the step of forming the first
contact hole and the second contact hole and the step of forming the
first reflective layer.

22. A method for manufacturing a light-emitting diode (LED) structure,
comprising: forming an illuminant epitaxial structure on a substrate,
wherein the illuminant epitaxial structure comprises: a first
conductivity type semiconductor layer, disposed on the substrate; an
active layer, disposed on a first part of the first conductivity type
semiconductor layer and exposing a second part of the first conductivity
type semiconductor layer; and a second conductivity type semiconductor
layer, disposed on the active layer and having a conductivity type
different from that of the first conductivity type semiconductor layer;
forming a first conductivity type contact layer on the second part of the
first conductivity type semiconductor layer; forming a second
conductivity type contact layer on the second conductivity type
semiconductor layer; forming a first reflective layer on the first
conductivity type contact layer; forming a second reflective layer on the
second conductivity type contact layer; forming a transparent insulating
layer covering the illuminant epitaxial structure, the first reflective
layer and the second reflective layer; forming a first contact hole and a
second contact hole in the transparent insulating layer, wherein the
first contact hole and the second contact hole respectively expose a part
of the first reflective layer and a part of the second reflective layer;
forming a first barrier layer extending on and covering the first contact
hole and a part of a surface of the transparent insulating layer; forming
a second barrier layer extending on and covering the second contact hole
and the other part of the surface of the transparent insulating layer;
forming a first conductivity type electrode on the first barrier layer
and filling up the first contact hole; and forming a second conductivity
type electrode on the second barrier layer and filling up the second
contact hole.

23. The method for manufacturing an LED structure according to claim 22,
wherein the first conductivity type electrode and the second conductivity
type electrode are disposed in the same plane.

24. The method for manufacturing an LED structure according to claim 22,
wherein the step of forming the transparent insulating layer comprises
forming a transparent oxide layer by spin coating to serve as the
transparent insulating layer.

25. The method for manufacturing an LED structure according to claim 22,
wherein the step of forming the first contact hole and the second contact
hole further comprises making a sidewall of the first contact hole and a
sidewall of the second contact hole be both inclined relative to the
illuminant epitaxial structure.

26. The method for manufacturing an LED structure according to claim 22,
further comprising forming at least one pattern structure in the surface
of the transparent insulating layer between the step of forming the first
contact hole and the second contact hole and the step of forming the
first barrier layer.

[0004] In the LED structure 124, the buffer layer 102 is disposed on the
substrate 100. The n-type semiconductor layer 104 is disposed on the
buffer layer 102. The active layer 106 is disposed on a part of the
n-type semiconductor layer 104, so that the n-type semiconductor layer
104 has an exposed part 110. The p-type semiconductor layer 108 is
disposed on the active layer 106. The p-type ohmic contact layer 112 and
the reflective layer 114 are stacked in sequence on the p-type
semiconductor layer 108. The p-type electrode 120 is disposed on a part
of the reflective layer 114. Furthermore, the n-type ohmic contact layer
116 and the n-type electrode 118 are stacked in sequence on the exposed
part 110 of the n-type semiconductor layer 104. The passivation layer 122
covers the p-type electrode 120, the reflective layer 114, the p-type
ohmic contact layer 112, the p-type semiconductor layer 108, the active
layer 106, the n-type semiconductor layer 104, the n-type ohmic contact
layer 116 and the n-type electrode 118, and exposes a part of the p-type
electrode 120 and a part of the n-type electrode 118.

[0005] In the conventional LED structure 124, the p-type ohmic contact
layer 112 together with the reflective layer 114 directly contact the
p-type semiconductor layer 108. When the LED structure 124 is operating
under a large current for a long time, the heat generated by the active
layer 106 easily deteriorates the reflective layer 114, and thus not only
the power of the device is attenuated but also the luminous efficiency of
the device may be influenced.

[0006] Furthermore, the flip-chip process requires the n-type electrode
118 and the p-type electrode 120 to have a large area. However, the
n-type electrode 118 of the conventional LED structure 124 is directly
disposed on the n-type ohmic contact layer 116, so when the n-type
semiconductor layer 104 is defined, a larger area needs to be removed to
enable the exposed part 110 of the n-type semiconductor layer 104 to have
a large area, for disposing the n-type ohmic contact layer 116 and the
n-type electrode 118 having the large area. Yet, as shown in FIG. 1, the
increase of the area of the n-type ohmic contact layer 116 and the n-type
electrode 118 will relatively reduce the light-emitting area of the
active layer 108, thus reducing the luminous efficiency of the LED
structure 124.

SUMMARY OF THE INVENTION

[0007] Accordingly, an aspect of the present invention is directed to an
LED structure and a method for manufacturing the same. A transparent
insulating layer is used to separate the reflective layer and the
illuminant epitaxial structure, thus reducing the influence of the heat
generated by the illuminant epitaxial structure on the stability of the
reflective layer during high power operation.

[0008] Another aspect of the present invention is directed to an LED
structure and a method for manufacturing the same, in which two
conductivity type electrodes may be both disposed on the transparent
insulating layer, thus reducing the area of the contact electrode and
increasing the overall light-emitting area, and further improving the
luminous efficiency of the LED structure.

[0009] Yet another aspect of the present invention is directed to an LED
structure and a method for manufacturing the same, in which at least one
pattern structure may be fabricated on the transparent insulating layer
to control the light output direction and angle of the LED structure,
thus improving the light extraction efficiency.

[0010] A further aspect of the present invention is directed to an LED
structure and a method for manufacturing the same, in which two
conductivity type electrodes have contact plugs extending to the contact
layer, and the contact plugs may serve as a heat flow passage of the
illuminant epitaxial structure, thus reducing the influence of the heat
generated in operation on the LED structure.

[0011] An alternative aspect of the present invention is directed to an
LED structure and a method for manufacturing the same, in which two
conductivity type electrodes may be lifted and disposed on the
transparent insulating layer, so that not only the area of the electrode
can be increased but also the two conductivity type electrodes can be
disposed in the same plane, which greatly reduces the difficulty of
flip-chip, thus improving the reliability of the flip-chip process.

[0012] In one aspect of the present invention, an LED structure is
provided. In one embodiment, the LED structure includes a substrate, an
illuminant epitaxial structure, a first conductivity type contact layer,
a second conductivity type contact layer, a transparent insulating layer,
a first reflective layer, a second reflective layer, a first barrier
layer, a second barrier layer, a first conductivity type electrode and a
second conductivity type electrode. The illuminant epitaxial structure
includes: a first conductivity type semiconductor layer disposed on the
substrate; an active layer disposed on a first part of the first
conductivity type semiconductor layer and exposing a second part of the
first conductivity type semiconductor layer; and a second conductivity
type semiconductor layer disposed on the active layer and having a
conductivity type different from that of the first conductivity type
semiconductor layer. The first conductivity type contact layer is
disposed on the second part of the first conductivity type semiconductor
layer. The second conductivity type contact layer is disposed on the
second conductivity type semiconductor layer. The transparent insulating
layer covers the illuminant epitaxial structure, the first conductivity
type contact layer and the second conductivity type contact layer and has
a surface, in which the transparent insulating layer includes a first
contact hole and a second contact hole respectively exposing a part of
the first conductivity type contact layer and a part of the second
conductivity type contact layer. The first reflective layer extends on
and covers the first contact hole and a part of the surface of the
transparent insulating layer. The second reflective layer extends on and
covers the second contact hole and the other part of the surface of the
transparent insulating layer. The first barrier layer and the second
barrier layer respectively cover the first reflective layer and the
second reflective layer. The first conductivity type electrode is
disposed on the first barrier layer and fills up the first contact hole.
The second conductivity type electrode is disposed on the second barrier
layer and fills up the second contact hole.

[0013] In another aspect of the present invention, an LED structure is
further provided. In one embodiment, the LED structure includes a
substrate, an illuminant epitaxial structure, a first conductivity type
contact layer, a second conductivity type contact layer, a first
reflective layer, a second reflective layer, a transparent insulating
layer, a first barrier layer, a second barrier layer, a first
conductivity type electrode and a second conductivity type electrode. The
illuminant epitaxial structure includes: a first conductivity type
semiconductor layer disposed on the substrate; an active layer disposed
on a first part of the first conductivity type semiconductor layer and
exposing a second part of the first conductivity type semiconductor
layer; and a second conductivity type semiconductor layer disposed on the
active layer and having a conductivity type different from that of the
first conductivity type semiconductor layer. The first conductivity type
contact layer is disposed on the second part of the first conductivity
type semiconductor layer. The second conductivity type contact layer is
disposed on the second conductivity type semiconductor layer. The first
reflective layer is stacked on the first conductivity type contact layer.
The second reflective layer is stacked on the second conductivity type
contact layer. The transparent insulating layer covers the illuminant
epitaxial structure, the first reflective layer and the second reflective
layer and has a surface, in which the transparent insulating layer
includes a first contact hole and a second contact hole respectively
exposing a part of the first reflective layer and a part of the second
reflective layer. The first barrier layer extends on and covers the first
contact hole and a part of the surface of the transparent insulating
layer. The second barrier layer extends on and covers the second contact
hole and the other part of the surface of the transparent insulating
layer. The first conductivity type electrode is disposed on the first
barrier layer and fills up the first contact hole. The second
conductivity type electrode is disposed on the second barrier layer and
fills up the second contact hole.

[0014] According to one embodiment of the present invention, the first
conductivity type electrode and the second conductivity type electrode
are disposed in the same plane.

[0015] According to another embodiment of the present invention, a
sidewall of the first contact hole and a sidewall of the second contact
hole are both inclined relative to the illuminant epitaxial structure.

[0016] In a further aspect of the present invention, a method for
manufacturing an LED structure is provided. In one embodiment, the method
includes the following steps. An illuminant epitaxial structure is formed
on a substrate. The illuminant epitaxial structure includes: a first
conductivity type semiconductor layer disposed on the substrate; an
active layer disposed on a first part of the first conductivity type
semiconductor layer and exposing a second part of the first conductivity
type semiconductor layer; a second conductivity type semiconductor layer
disposed on the active layer and having a conductivity type different
from that of the first conductivity type semiconductor layer. A first
conductivity type contact layer is formed on the second part of the first
conductivity type semiconductor layer. A second conductivity type contact
layer is formed on the second conductivity type semiconductor layer. A
transparent insulating layer covering the illuminant epitaxial structure,
the first conductivity type contact layer and the second conductivity
type contact layer is formed. A first contact hole and a second contact
hole are formed in the transparent insulating layer, in which the first
contact hole and the second contact hole respectively expose a part of
the first conductivity type contact layer and a part of the second
conductivity type contact layer. A first reflective layer extending on
and covering the first contact hole and a part of a surface of the
transparent insulating layer is formed. A second reflective layer
extending on and covering the second contact hole and the other part of
the surface of the transparent insulating layer is formed. A first
barrier layer and a second barrier layer respectively covering the first
reflective layer and the second reflective layer are formed. A first
conductivity type electrode is formed on the first barrier layer and
fills up the first contact hole. A second conductivity type electrode is
formed on the second barrier layer and fills up the second contact hole.

[0017] In yet another aspect of the present invention, a method for
manufacturing an LED structure is further provided. In one embodiment,
the method includes the following steps. An illuminant epitaxial
structure is formed on a substrate. The illuminant epitaxial structure
includes: a first conductivity type semiconductor layer disposed on the
substrate; an active layer disposed on a first part of the first
conductivity type semiconductor layer and exposing a second part of the
first conductivity type semiconductor layer; and a second conductivity
type semiconductor layer disposed on the active layer and having a
conductivity type different from that of the first conductivity type
semiconductor layer. A first conductivity type contact layer is formed on
the second part of the first conductivity type semiconductor layer. A
second conductivity type contact layer is formed on the second
conductivity type semiconductor layer. A first reflective layer is formed
on the first conductivity type contact layer. A second reflective layer
is formed on the second conductivity type contact layer. A transparent
insulating layer covering the illuminant epitaxial structure, the first
reflective layer and the second reflective layer is formed. A first
contact hole and a second contact hole are formed in the transparent
insulating layer, in which the first contact hole and the second contact
hole respectively expose a part of the first reflective layer and a part
of the second reflective layer. A first barrier layer extending on and
covering the first contact hole and a part of a surface of the
transparent insulating layer is formed. A second barrier layer extending
on and covering the second contact hole and the other part of the surface
of the transparent insulating layer is formed. A first conductivity type
electrode is formed on the first barrier layer and fills up the first
contact hole. A second conductivity type electrode is formed on the
second barrier layer and fills up the second contact hole.

[0018] According to one embodiment of the present invention, the step of
forming the first contact hole and the second contact hole further
includes making a sidewall of the first contact hole and a sidewall of
the second contact hole be both inclined relative to the illuminant
epitaxial structure.

[0019] According to another embodiment of the present invention, the
method for manufacturing an LED structure further includes forming at
least one pattern structure in the surface of the transparent insulating
layer between the step of forming the first contact hole and the second
contact hole and the step of forming the first barrier layer.

[0020] According to the embodiments of the present invention, the
transparent insulating layer is used to separate the reflective layer and
the illuminant epitaxial structure, thus effectively reducing the
influence of the heat generated during high power operation on the LED
device. Furthermore, since the two conductivity type electrodes may be
both lifted and disposed on the transparent insulating layer, the entire
light-emitting area is increased and the area of the electrode is
expanded. The two conductivity type electrodes can be disposed in the
same plane, which is beneficial to reducing the difficulty of the
flip-chip process, thus improving the reliability of the flip-chip
process. Moreover, at least one pattern structure may be disposed on the
transparent insulating layer to control the light-emitting direction of
the LED structure, thus improving the light extraction efficiency of the
device. Meanwhile, the two conductivity type electrodes have contact
plugs extending to the contact layer. Since the contact plugs may serve
as the heat flow passage of the illuminant epitaxial structure, the
influence of the heat generated in operation on the LED structure can be
reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings illustrate one or more embodiments of the
invention and together with the written description, serve to explain the
principles of the invention. Wherever possible, the same reference
numbers are used throughout the drawings to refer to the same or like
elements of an embodiment, and wherein:

[0022] FIG. 1 is a schematic sectional view of a conventional LED
structure;

[0023] FIGS. 2A to 2E are sectional views illustrating processes of an LED
structure according to one embodiment of the present invention;

[0024]FIG. 2F is a schematic view of distribution of a first conductivity
type contact layer, a second conductivity type contact layer and
corresponding contact holes of an LED structure according to one
embodiment of the present invention;

[0025]FIG. 2G is a schematic sectional view of a package structure of an
LED structure according to one embodiment of the present invention;

[0026] FIG. 3 is a sectional view of an LED structure according to another
embodiment of the present invention; and

[0027] FIGS. 4A to 4E are sectional views illustrating processes of an LED
structure according to yet another embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0028] The present invention will now be described more fully hereinafter
with reference to the accompanying drawings, in which exemplary
embodiments of the invention are shown. This invention may, however, be
embodied in many different forms and should not be construed as limited
to the embodiments set forth herein. Rather, these embodiments are
provided so that this disclosure will be thorough and complete, and will
fully convey the scope of the invention to those skilled in the art. Like
reference numerals refer to like elements throughout.

[0029] Example embodiments are described herein with reference to
cross-sectional illustrations that are schematic illustrations of
idealized embodiments (and intermediate structures) of example
embodiments. As such, variations from the shapes of the illustrations as
a result, for example, of manufacturing techniques and/or tolerances, are
to be expected. Thus, example embodiments should not be construed as
limited to the shapes of regions illustrated herein but are to include
deviations in shapes that result, for example, from manufacturing. For
example, an implanted region illustrated as a rectangle will, typically,
have rounded or curved features and/or a gradient of implant
concentration at its edges rather than a binary change from implanted to
non-implanted region. Likewise, a buried region formed by implantation
may result in some implantation in the region between the buried region
and the surface through which the implantation takes place. Thus, the
regions illustrated in the figures are schematic in nature and their
shapes are not intended to illustrate the actual shape of a region of a
device and are not intended to limit the scope of example embodiments.

[0030] It will be understood that when an element or layer is referred to
as being "on," "connected to," "coupled to," or "covering" another
element or layer, it may be directly on, connected to, coupled to, or
covering the other element or layer or intervening elements or layers may
be present. In contrast, when an element is referred to as being
"directly on" another element, there are no intervening elements present.
As used herein, the term "and/or" includes any and all combinations of
one or more of the associated listed items.

[0031] It will be understood that, although the terms first, second, third
etc. may be used herein to describe various elements, components,
regions, layers and/or sections, these elements, components, regions,
layers and/or sections should not be limited by these terms. These terms
are only used to distinguish one element, component, region, layer or
section from another element, component, region, layer or section. Thus,
a first element, component, region, layer or section discussed below
could be termed a second element, component, region, layer or section
without departing from the teachings of the present invention.

[0032] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of the
invention. As used herein, the singular forms "a", "an" and "the" are
intended to include the plural forms as well, unless the context clearly
indicates otherwise. It will be further understood that the terms
"comprises" and/or "comprising," or "includes" and/or "including" or
"has" and/or "having" when used in this specification, specify the
presence of stated features, regions, integers, steps, operations,
elements, and/or components, but do not preclude the presence or addition
of one or more other features, regions, integers, steps, operations,
elements, components, and/or groups thereof.

[0033] Furthermore, relative terms, such as "lower" or "bottom" and
"upper" or "top," may be used herein to describe one element's
relationship to another element as illustrated in the Figures. It will be
understood that relative terms are intended to encompass different
orientations of the device in addition to the orientation depicted in the
Figures. For example, if the device in one of the figures is turned over,
elements described as being on the "lower" side of other elements would
then be oriented on "upper" sides of the other elements. The exemplary
term "lower", can therefore, encompasses both an orientation of "lower"
and "upper," depending of the particular orientation of the figure.
Similarly, if the device in one of the figures is turned over, elements
described as "below" or "beneath" other elements would then be oriented
"above" the other elements. The exemplary terms "below" or "beneath" can,
therefore, encompass both an orientation of above and below.

[0034] Unless otherwise defined, all terms (including technical and
scientific terms) used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which this invention
belongs. It will be further understood that terms, such as those defined
in commonly used dictionaries, should be interpreted as having a meaning
that is consistent with their meaning in the context of the relevant art
and the present disclosure, and will not be interpreted in an idealized
or overly formal sense unless expressly so defined herein.

[0035] FIGS. 2A to 2E are sectional views illustrating manufacturing
processes of an LED structure according to one embodiment of the present
invention. In this embodiment, firstly, a transparent substrate 200 is
provided. The material of the substrate 200 may be for example sapphire.
Then, a buffer layer 202 is selectively formed on the substrate 200 by
epitaxy, e.g. Metal-Organic Chemical Vapor Deposition (MOCVD). The
material of the buffer layer 202 may be an undoped semiconductor, e.g.
undoped GaN-series material. Afterwards, an illuminant epitaxial
structure is grown on the buffer layer 202 by epitaxy, e.g. MOCVD. In
this embodiment, the illuminant epitaxial structure may include a first
conductivity type semiconductor layer 204, an active layer 210 and a
second conductivity type semiconductor layer 212 stacked in sequence on
the buffer layer 202. The first conductivity type semiconductor layer 204
and the second conductivity type semiconductor layer 212 have different
conductivity types. For example, one of the first conductivity type
semiconductor layer 204 and the second conductivity type semiconductor
layer 212 is n-type, and the other is p-type. The material of the
illuminant epitaxial structure may be for example a GaN-series material.
The active layer 210 may be for example a multiple quantum well (MQW)
structure.

[0036] As shown in FIG. 2A, after the illuminant epitaxial structure is
grown, the illuminant epitaxial structure is defined by for example
lithography and etching to remove a part of the second conductivity type
semiconductor layer 212, a part of the active layer 210 and a part of the
first conductivity type semiconductor layer 204, thus forming a mesa.
After the mesa is defined, the first conductivity type semiconductor
layer 204 has a first part 206 and a second part 208, in which the second
conductivity type semiconductor layer 212 and the active layer 210 are
disposed on the first part 206 of the first conductivity type
semiconductor layer 204, and the second part 208 is exposed.

[0037] Then, a first conductivity type contact layer 214 and a second
conductivity type contact layer 216 are formed by for example
evaporation. As shown in FIG. 2B, the first conductivity type contact
layer 214 and the second conductivity type contact layer 216 are
respectively disposed on the second part 208 of the first conductivity
type semiconductor layer 204 and a part of the second conductivity type
semiconductor layer 212. The first conductivity type contact layer 214
and the second conductivity type contact layer 216 may be ohmic contact
layers. When the first conductivity type is n-type, the material of the
first conductivity type contact layer 214 may be for example indium tin
oxide (ITO), TiAl, Cr/Pt/Au or Cr/Au. When the second conductivity type
is p-type, the second conductivity type contact layer 216 may be a
transparent oxide structure, e.g. a monolayer or multilayer structure of
ITO, ZnO, AZO, GZO, In2O3 and SnO2. In another embodiment,
the material of the second conductivity type contact layer 216 may be
Ni/Au or Ni/Ag.

[0038] Thereafter, as shown in FIG. 2C, a transparent insulating layer 218
is formed by deposition or coating, e.g. spin coating, to cover the first
conductivity type semiconductor layer 204, the active layer 210 and the
second conductivity type semiconductor layer 212 of the illuminant
epitaxial structure, as well as the first conductivity type contact layer
214 and the second conductivity type contact layer 216. The transparent
insulating layer 218 preferably has a planarized surface 220, and the
surface 220 is disposed opposite to the illuminant epitaxial structure.
In an example, the material of the transparent insulating layer 218 may
be for example spin on glass (SOG), a high polymer, SiO2 or
TiO2. The thickness of the transparent insulating layer 218 is
preferably between 0.5 μm and 100 μm. In one embodiment transparent
oxide layer is formed by spin coating to serve as transparent insulating
layer 218.

[0039] Then, a part of the transparent insulating layer 218 is removed by
for example etching to form contact holes 222, 224 in the transparent
insulating layer 218. As shown in FIG. 2D, the contact holes 222, 224
respectively expose a part of the first conductivity type contact layer
214 and a part of the second conductivity type contact layer 216.

[0040] The LED structure may include at least one first conductivity type
contact layer 214 and at least one second conductivity type contact layer
216, that is, the number of the first conductivity type contact layer 214
and the second conductivity type contact layer 216 may respectively be
one or more. FIG. 2F is a schematic top view of distribution of a first
conductivity type contact layer, a second conductivity type contact layer
and corresponding contact holes of an LED structure according to one
embodiment of the present invention. Each first conductivity type contact
layer 214 is configured with a contact hole preset region 222a, and each
second conductivity type contact layer 216 is configured with a contact
hole preset region 224a. The contact hole 222 is formed on the contact
hole preset region 222a of the first conductivity type contact layer 214,
and the contact hole 224 is formed on the contact hole preset region 224a
of the second conductivity type contact layer 216.

[0041] Referring to FIG. 2E, then, reflective layers 226, 230 are formed.
The reflective layer 226 extends on and covers the contact hole 222 and a
part of the surface 220 of the transparent insulating layer 218. The
reflective layer 230 extends on and covers the contact hole 224 and the
other part of the surface 220 of the transparent insulating layer 218.
The reflective layers 226 and 230 are not in contact. In one embodiment,
the reflective layers 226, 230 preferably have a structure of at least
two layers. That is, at least one attachment film is firstly formed, and
then a reflective film is formed on the attachment film. The material of
the attachment film may be for example Ti, Ni or TiW alloy, and the
material of the reflective film may be for example Al or Ag.

[0042] Then, barrier layers 228, 232 respectively covering the reflective
layers 226, 230 are selectively formed. The barrier layers 228 and 232
are not in contact. The material of the barrier layers 228, 232 may be
for example Ti, TiW alloy, W, Pt, Ni or any combinations thereof. The
barrier layers 228, 232 may respectively prevent the diffusion between
the reflective layer 226 and a first conductivity type electrode 234
formed in the following process and the diffusion between the reflective
layer 230 and a second conductivity type electrode 236 formed in the
following process.

[0043] Thereafter, the first conductivity type electrode 234 and the
second conductivity type electrode 236 are formed by for example
evaporation, sputtering, electroplating or chemical plating, thus
finishing the fabrication of an LED structure 242. The first conductivity
type electrode 234 is disposed on the barrier layer 228 and fills up the
contact hole 222. The second conductivity type electrode 236 is disposed
on the barrier layer 232 and fills up the contact hole 224. The part of
the first conductivity type electrode 234 disposed on the contact hole
222 may be referred to as a contact plug 238, and the part of the second
conductivity type electrode 236 disposed on the contact hole 224 may be
referred to as a contact plug 240. In one embodiment, the first
conductivity type electrode 234 and the second conductivity type
electrode 236 may include a multilayer structure, e.g. Au or Ni and a
eutectic metal of AuSn or AgSnCu disposed above Au or Ni.

[0044] In one embodiment, in addition to the contact plugs 238, 240, the
first conductivity type electrode 234 and the second conductivity type
electrode 236 are preferably disposed in the same plane, as shown in FIG.
2E. After the fabrication of the LED structure 242 is finished, a
packaging process of the LED structure 242 may be carried out. In this
embodiment, the LED structure 242 is suitable for a flip-chip packaging
process. During the flip-chip packaging process of the LED structure 242,
solder bumps 254, 256 may be firstly formed on the first conductivity
type electrode 234 and the second conductivity type electrode 236
respectively. Meanwhile, a package substrate 258 is provided. Then, as
shown in FIG. 2G, the LED structure 242 is inverted and covered on a
preset region of the package substrate 258, thus substantially finishing
the flip-chip packaging of the LED structure 242. The first conductivity
type electrode 234 and the second conductivity type electrode 236 of the
LED structure 242 are electrically connected to a preset circuit on the
package substrate 258 respectively by the solder bumps 254, 256.

[0045] Since the first conductivity type electrode 234 and the second
conductivity type electrode 236 are disposed in the same plane, the
difficulty of the flip-chip of the LED structure 242 is greatly reduced,
thus improving the reliability of the flip-chip process.

[0046] In the present invention, a pattern structure may also be
fabricated on the transparent insulating layer of the LED structure to
control the light output direction of the LED structure. FIG. 3 is a
sectional view of an LED structure according to another embodiment of the
present invention. The architecture of the LED structure 252 is
substantially the same as that of the LED structure 242 in the above
embodiment. The difference of the two lies in that sidewalls of the two
contact holes 222, 224 of LED structure 242 are substantially
perpendicular to the illuminant epitaxial structure, while a sidewall 246
of a contact hole 244 and a sidewall 250 of a contact hole 248 of the LED
structure 252 are both inclined relative to the illuminant epitaxial
structure.

[0047] In this embodiment, by making the sidewall 246 of the contact hole
244 and the sidewall 250 of the contact hole 248 be inclined relative to
the illuminant epitaxial structure when forming the contact holes 244,
248 in the transparent insulating layer 218, the reflection direction of
the light emitted to the reflective layers 226, 230 may be changed, thus
controlling the light output direction and angle of the LED structure
252.

[0048] In other embodiments, in addition to changing the inclined angle of
the sidewall of the contact hole relative to the illuminant epitaxial
structure, the surface 220 of the transparent insulating layers 218 may
be patterned so that the surface 220 of the transparent insulating layer
218 have one or more pattern structures, e.g. regular pattern structures
or irregular pattern structures. By disposing at least one pattern
structure on the surface 220 of the transparent insulating layer 218
between the step of forming the contact holes 222, 224 or contact holes
244, 248 in the transparent insulating layer 218 and the step of forming
the reflective layers 226, 230, the light output direction and angle of
the LED structure 242 or 252 may be controlled.

[0049] FIGS. 4A to 4E are sectional views illustrating manufacturing
processes of an LED structure according to yet another embodiment of the
present invention. In this embodiment, firstly, a transparent substrate
300 is provided, in which the material of the substrate 300 may be for
example sapphire. Then, a buffer layer 302 is selectively grown on the
substrate 300 by epitaxy, e.g. MOCVD. The material of the buffer layer
302 may be an undoped semiconductor, e.g. undoped GaN-series material.

[0050] Afterwards, an illuminant epitaxial structure is grown on the
buffer layer 302 by epitaxy, e.g. MOCVD. In this embodiment, the
illuminant epitaxial structure may include a first conductivity type
semiconductor layer 304, an active layer 310 and a second conductivity
type semiconductor layer 312 stacked in sequence on the buffer layer 302.
The first conductivity type semiconductor layer 304 and the second
conductivity type semiconductor layer 312 have different conductivity
types. For example, one of the first conductivity type semiconductor
layer 304 and the second conductivity type semiconductor layer 312 is
n-type, and the other is p-type. The material of the illuminant epitaxial
structure may be for example a GaN-series material. The active layer 310
may be for example an MQW structure.

[0051] Then, as shown in FIG. 4A, the illuminant epitaxial structure is
defined by for example lithography and etching to remove a part of the
second conductivity type semiconductor layer 312, a part of the active
layer 310 and a part of the first conductivity type semiconductor layer
304, thus forming a mesa. After the illuminant epitaxial structure is
defined, the first conductivity type semiconductor layer 304 has a first
part 306 and a second part 308. The second conductivity type
semiconductor layer 312 and the active layer 310 are disposed on the
first part 306 of the first conductivity type semiconductor layer 304,
and the second part 308 is exposed.

[0052] Thereafter, a first conductivity type contact layer 314 and a
second conductivity type contact layer 318 are respectively formed on the
second part 308 of the first conductivity type semiconductor layer 304
and a part of the second conductivity type semiconductor layer 312 by for
example evaporation. Likewise, the LED structure may include at least one
first conductivity type contact layer 314 and at least one second
conductivity type contact layer 318. That is, the number of the first
conductivity type contact layer 314 and the number of the second
conductivity type contact layer 318 are both at least one. Preferably,
the first conductivity type contact layer 314 and the second conductivity
type contact layer 318 may be for example ohmic contact layers. When the
first conductivity type is n-type, the material of the first conductivity
type contact layer 314 may be for example ITO, TiAl, Cr/Pt/Au or Cr/Au.
When the second conductivity type is p-type, the second conductivity type
contact layer 318 may be a transparent oxide structure, e.g. a monolayer
or multilayer structure of ITO, ZnO, AZO, GZO, In2O3 and
SnO2. In another embodiment, the material of the second conductivity
type contact layer 318 may be Ni/Au or Ni/Ag.

[0053] Thereafter, as shown in FIG. 4B, reflective layers 316, 320 are
respectively formed on the first conductivity type contact layer 314 and
the second conductivity type contact layer 318. In one embodiment, the
reflective layers 316, 320 preferably have a structure of at least two
layers, in which each of the reflective layers 316, 320 includes at least
one attachment film and a reflective film stacked in sequence. The
material of the attachment film may be for example Ti, Ni or TiW alloy,
and the material of the reflective film may be for example Al or Ag.

[0054] Then, as shown in FIG. 4c, a transparent insulating layer 322 is
formed by deposition or coating, e.g. spin coating, to cover the first
conductivity type semiconductor layer 304, the active layer 310 and the
second conductivity type semiconductor layer 312 of the illuminant
epitaxial structure, as well as the first conductivity type contact layer
314, the second conductivity type contact layer 318, the reflective
layers 316, 320. The transparent insulating layer 322 preferably has a
planarized surface 324, and the surface 324 is disposed opposite to the
illuminant epitaxial structure. In an example, the material of the
transparent insulating layer 322 may be a transparent oxide layer, e.g.
SOG, a high polymer, SiO2 or TiO2. The thickness of the
transparent insulating layer 322 is preferably between 0.5 μm and 100
μm.

[0055] Then, as shown in FIG. 4D, a part of the transparent insulating
layer 322 is removed by for example etching to form contact holes 326,
328 in the transparent insulating layer 322. The contact holes 326, 328
respectively expose a part of the reflective layer 316 and a part of the
reflective layer 320.

[0056] Referring to FIG. 4E, thereafter, barrier layers 330, 332 are
selectively formed. The barrier layer 330 extends on and covers the
contact hole 326 and a part of the surface 324 of the transparent
insulating layer 322. The barrier layer 332 extends on and covers the
contact hole 328 and the other part of the surface 324 of the transparent
insulating layer 322. The barrier layers 330 and 332 are not in contact.
The material of the barrier layers 330, 332 may be for example Ti, TiW
alloy, W, Pt, Ni or any combination thereof. The barrier layers 330, 332
are respectively used to prevent the diffusion between the reflective
layer 316 and a first conductivity type electrode 334 formed in the
following process and the diffusion between the reflective layer 320 and
a second conductivity type electrode 336 formed in the following process.

[0057] Then, as shown in FIG. 4E, the first conductivity type electrode
334 and the second conductivity type electrode 336 are formed by for
example evaporation, sputtering, electroplating or chemical plating, thus
finishing the fabrication of an LED structure 342. The first conductivity
type electrode 334 is disposed on the barrier layer 330 and fills up the
contact hole 326. The second conductivity type electrode 336 is disposed
on the barrier layer 332 and fills up the contact hole 328. In the LED
structure 342, the part of the first conductivity type electrode 334
disposed on the contact hole 326 may be referred to as a contact plug
338, and the part of the second conductivity type electrode 336 disposed
on the contact hole 328 may be referred to as a contact plug 340. In one
embodiment, the first conductivity type electrode 334 and the second
conductivity type electrode 336 may include a multilayer structure, and
the multilayer structure includes for example Au or Ni and a eutectic
metal of AuSn or AgSnCu disposed above Au or Ni.

[0058] In one embodiment, as shown in FIG. 4E, in addition to the contact
plugs 338, 340, the first conductivity type electrode 334 and the second
conductivity type electrode 336 are preferably disposed in the same
plane. After the fabrication of the LED structure 342 is finished, a
packaging process may be carried out. In this embodiment, the LED
structure 342 is suitable for a flip-chip packaging process. Since the
first conductivity type electrode 338 and the second conductivity type
electrode 340 are disposed in the same plane, the difficulty of the
flip-chip of the LED structure 342 is greatly reduced, thus improving the
reliability of the flip-chip process.

[0059] In this embodiment, similar to the embodiment of FIG. 3, sidewalls
of the two contact holes 326, 328 of the LED structure 342 are both
inclined relative to the illuminant epitaxial structure, thus controlling
the light output direction and angle of the LED structure 342.
Furthermore, at least one pattern structure, e.g. a regular pattern
structure or an irregular pattern structure may also be disposed on the
surface 324 of the transparent insulating layer 322 between the step of
forming the contact holes 326, 328 in the transparent insulating layer
322 and the step of forming the barrier layers 330, 332, so as to change
the light output direction and angle of the LED structure 342.

[0060] It can be seen from the above embodiments that, among other things,
an advantage of the present invention lies in that the present invention
uses the transparent insulating layer to separate the reflective layer
and the illuminant epitaxial structure, thus reducing the influence of
the heat generated by the illuminant epitaxial structure during high
power operation on the stability of the reflective layer.

[0061] It can be seen from the above embodiments that, among other things,
another advantage of the present invention lies in that the two
conductivity type electrodes of the LED structure of the present
invention may be both disposed on the transparent insulating layer, thus
reducing the area of the contact electrode and increasing the overall
light-emitting area, and further improving the luminous efficiency of the
LED structure.

[0062] It can be seen from the above embodiments that, among other things,
yet another advantage of the present invention lies in that in the method
for manufacturing an LED structure of the present invention, at least one
pattern structure may be fabricated on the transparent insulating layer
to control the light output direction and angle of the LED structure,
thus improving the light extraction efficiency.

[0063] It can be seen from the above embodiments that, among other things,
a further advantage of the present invention lies in that the two
conductivity type electrodes of the present invention have contact plugs
extending to the contact layer, and the contact plugs may serve as the
heat flow passage of the illuminant epitaxial structure, thus reducing
the influence of the heat generated in operation on the LED structure.

[0064] It can be seen from the above embodiments that, among other things,
an alternative advantage of the present invention lies in that the two
conductivity type electrodes of the present invention may be lifted and
disposed on the transparent insulating layer, so that the area of the
electrode can be expanded, and the two conductivity type electrodes can
be disposed in the same plane, which greatly reduces the difficulty of
flip-chip, thus improving the reliability of the flip-chip process.

[0065] The foregoing description of the exemplary embodiments of the
invention has been presented only for the purposes of illustration and
description and is not intended to be exhaustive or to limit the
invention to the precise forms disclosed. Many modifications and
variations are possible in light of the above teaching.

[0066] The embodiments are chosen and described in order to explain the
principles of the invention and their practical application so as to
activate others skilled in the art to utilize the invention and various
embodiments and with various modifications as are suited to the
particular use contemplated. Alternative embodiments will become apparent
to those skilled in the art to which the present invention pertains
without departing from its spirit and scope. Accordingly, the scope of
the present invention is defined by the appended claims rather than the
foregoing description and the exemplary embodiments described therein.